Preparation Steps

• Line two baking sheets with parchment paper. Place the Cadbury Mini Eggs inside a folded kitchen towel and gently tap with a rolling pin or skillet until broken into a mix of chunky and small bits; set aside a handful of the larger pieces for topping.
• In a medium bowl, whisk together the flour, baking soda, fine sea salt, and espresso powder.
• In a large mixing bowl, beat the butter, brown sugar, and granulated sugar on medium speed until light and creamy, about 2 minutes, scraping the bowl once.
• Beat in the egg, then the egg yolk, followed by the vanilla, mixing just until smooth.
• Add the dry ingredients in two additions on low speed, stopping when a few streaks of flour remain. Fold in the mini chocolate chips and about three-quarters of the chopped Mini Eggs with a spatula.
• Cover and chill the dough for 20 minutes to firm slightly and hydrate the flour.
• While the dough chills, preheat the oven to 365°F (185°C) with a rack in the center.
• Scoop the dough into 2-tablespoon mounds (about a medium cookie scoop) and arrange on prepared sheets, spacing about 2 1/2 inches apart. Lightly press a few reserved Mini Egg pieces onto the tops for a colorful finish.
• Bake one sheet at a time for 11–13 minutes, rotating the pan halfway through. The edges should be set and golden while the centers remain pale with a soft gloss.
• Remove from the oven and rap the baking sheet once on the counter to encourage crinkly edges. Sprinkle a tiny pinch of flaky sea salt over each cookie if using. Cool on the sheet for 10 minutes before transferring to a wire rack to cool completely.